I. Field of the Invention
The present invention relates to a device for use in recreational vehicles, marine vessels, and other such mobile self-contained living environments. The device provides instrumentation and control functions for the water plumbing system of such recreational vehicles.
II. Description of the Prior Art
Self contained recreational vehicles (RV's) and marine vessels contain an on-board supply tank of fresh water and an electric demand pump to provide water pressure to the plumbing system enabling flow to appliances such as faucets, a shower, or toilet which then drain into various waste tanks. As is known in the art, the plumbing system can be connected to an external pressurized water supply when available, such as hookups available from an RV park or dockside. Typically the connection is made by a standard garden hose.
Commercially available systems are typically installed to indicate the water level in the fresh water supply tank. U.S. Pat. No. 5,079,950 of McKiernan, U.S. Pat. No. 4,358,956 of Ruben et al, and U.S. Pat. No. 5,103,673 of Sawada et al are examples in the prior art which accomplish this level indication utilizing some assembly or sensor mounted in the tank. U.S. Pat. No. 4,145,927 of Larson is an example of level indication using a non-intrusive method by sensing the variation in capacitance between the walls of the tank as the water level changes. U.S. Pat. No. 4,739,658 of Slavik is an example of an extremely common implementation in the art utilizing commercially available conductive probes protruding into the tank at varying heights to sense the presence of water at different levels.
Typically in the art the fresh water tank is filled manually from a fill tube which is accessed from a hatch in the exterior of the vehicle. A relatively few commercially available RV's, typically more expensive luxury models have an installation permitting the manual opening of a valve to allow water flow from the external pressure source into the tank, a somewhat more convenient arrangement. U.S. Pat. No. 4,039,001 of Weldy uses a pressure switch to detect the presence of an externally available pressure to open a solenoid actuated valve so as to back-fill the tank with water automatically U.S. Pat. No. 4,744,385 of Houghton also provides means to use the external pressurized supply to flush and dump the waste tanks of the RV.
U.S. Pat. No. 4,109,604 of Reed relates to transport of RV's on water carriers and provision of fresh water and removal of waste water to and from the RV's so as to keep the center of gravity of the water such that the carrier stays level, and as such does not address the water pressure or levels of the tanks within the RV's.
The plumbing systems and fittings in RV's are typically made from lower pressure, light weight components relative to residential plumbing and therefore a water pressure regulator can be installed between the external water pressure source and the RV plumbing connection to protect the internal RV plumbing system from high municipal, park, or dockside pressure. Indication of the actual water pressure is normally not provided, and the more expensive water pressure regulators that do provide such indication unfortunately use only a mechanical dial gage which is installed at the water source, not at or within the RV for convenient inspection. The water pressure regulators commercially available to RV owners are normally of a simple spring diaphragm type and subject to frequent failure as they get stuck either open, closed, or in between. Failure of the water pressure regulator can therefore lead to reduced pressure, or worse, higher pressure than that recommended for RV-type plumbing, normally about 60 psi. This failure can occur without knowledge of the RV owner. Also, due to the lightweight nature of the plumbing and the constant vibration of the vehicle, the fittings of the plumbing system are prone to leaks. Depending on the size of the leak and the routing and location of the plumbing, some time normally passes before the leak is detected, usually after some degree of vehicle interior wood or carpet damage has occurred. An unattended vehicle or one with occupants asleep can incur a higher degree of damage, since either the external source will provide flow indefinitely if hooked up or, if not hooked up, the on board pump can empty the entire fresh water tank Further, the on board demand pump will run dry and heat up, causing permanent damage.
As is evidenced from the discussion of the prior art, there is a need in the art for improved instrumentation and control of water pressure. Further, although the prior art provides for instrumentation of water level, the best control of water level in the art is only to automatically fill the tank until full. As is known in the art, the added weight of a full tank is undesirable since the large weight of the water can severely detract from vehicle performance, particularly when traveling up grades in mountainous terrain. Further, the penalty in gas mileage and performance due to the added weight is often unnecessary since the owner of the RV may only need a fraction of a tank for a given trip or weekend. Also, when traveling, the RV owner often knows the occupants will only need such a fraction of a tank for the present travel segment, after which he may hook-up at an RV park for the night, for example, providing the opportunity to refill for the next leg of the journey. At this time the waste tanks can also be dumped. In addition to commercial RV parks, many rest areas on the nation's highways provide for such facilities. The ability to conveniently use such resources to refill the tank only partially would maintain the vehicle payload weight, gas mileage, and vehicle performance while meeting the water needs of the occupant(s).
There is a need in the art to provide the RV owner with improved control over fresh water supply level and the flexibility to automatically fill to a user selectable level.
Further, the prior art does not provide for the enabling of automatic filling from more than one location and as such does not provide for the convenience of performing this operation when hookups to the RV are being made at the external water supply access location.
Further, since in the prior art the filling of the water tank required the addition and installation of additional and expensive hardware components such as pressure switches, float valves and the like, there is a need for such a system which utilizes already existing instrumentation and does not have inherent difficulties in installation such as removing tanks, intrusively mounting float assemblies, and so forth.